1. Field of the Invention
The present invention relates to a breaker composition adapted to break the viscosity of a viscosified fluid to a desired low value at down hole conditions within a time period coincident with a formation stimulation time and to methods for making and using same.
More particularly, the present invention relates to a breaker composition including an effective amount of an alkali chlorite and/or hyperchlorite to reduce a viscosity of a polymer viscosified fluid to a desired low value at down hole conditions within a time period coincident with a formation stimulation time and to methods for making and using same.
2. Description of the Related Art
One of the key problems in the use of slick water, linear gels and crosslinked fluids for stimulation and fracturing applications is to find a composition and/or method that controllably breaks such polymer viscosified systems at bottom hole conditions. The ideal breakers are those that are in a liquid state and can be delivered under controlled or controllable conditions sufficient to reduce a down hole fluid viscosity to a desired low value during a formation stimulation, i.e., for a time not shorter than and not much longer than a time needed to complete the formation stimulation.
There are many effective oxidative breakers, acid breakers, terpenes breaker and enzymes breaker or combination thereof either in the form of a pure material, a solution, a suspension or an encapsulated form that most of the time break the fluid in shorter or longer periods of time than needed to complete the formation stimulation. These breakers are only effective in narrow ranges of temperatures, which are not necessarily identical to or similar to bottom hole conditions. These systems have been introduced and widely used by services companies including Halliburton, Shlumberger, BJ Services, Weatherford, Mich., Baroid, Baker Hughes, among others.
U.S. Pat. No. 5,413,178 disclosed a composition and method for breaking polymer viscosified fluids using an alkali metal chlorite or hypochlorite, which releases oxygen chloride in a controllable manner to break down the polymer structure, and, therefore, decrease the viscosity of the polymer viscosified fluids.
Although there are breakers known to decrease the viscosity of down hole fluids during stimulation and/or fracturing operations, there is still a need in the art for breaker systems and methods of use that can effectively lower the viscosity of a down hole fluid to desired low value under down hole conditions.